Zcash will activate the NU7 network upgrade on November 6th at 10:30 AM. The upgrade will be activated at block 3543405, at which time the system will reject version 4 transactions, rendering approximately $16 million worth of ZEC in the Sprout privacy pool unusable.
As of Thursday morning, approximately 12,226 ZEC remained in the Sprout pool, and holders were required to transfer their tokens out before the upgrade. ZIP 2003 reserves the possibility of restoring access through a future upgrade, but warns that the transfer function may never be reactivated.